Up to 4 standard tissue cassettes, each containing tissue samples with a maximum size of 4 x 15 x 15 mm, can be placed into a PAXgene Tissue FIX Container (50 ml). Alternatively, a single tissue sample with a maximum size of 20 x 20 x 20 mm can be fixed directly in a PAXgene Tissue FIX Container (50 ml). If using a larger tissue sample surrounded by fat (e.g., from a lymph node) or capsule (e.g., from kidney, liver or spleen tissue), partially cut into the tissue every 5 mm (lamination) to enhance permeation of the fixative reagent. If a sample is larger than recommended, the fast and even penetration of fixation reagent is compromised. In such cases, a reduction in the quality of tissue morphology and the integrity of nucleic acids may result.